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EPR Study of Dealuminated HY Zeolite and Silica Containing Cu-Mn-Zn Spinels: The Effect of Support

100%
Decyk P., Więckowski A., Najder-Kozdrowska L., Bilkova I., Ziółek M.
Acta Physica Polonica A
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2017
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vol. 132
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issue 1
38-44
EN
A mixture of antiferromagnetic Cu_{1.4}Mn_{1.6}O₄ and Cu_{0.5}Zn_{0.5}Mn₂O₄ or/and ZnMn₂O₄ spinels was prepared. Dealuminated HY zeolite and silica were doped by these Cu-Mn-Zn spinels. The materials were investigated by X-ray diffraction, the Fourier transform infrared spectroscopy and EPR spectroscopy. Additionally, all the samples were tested for their activity for isopropyl alcohol dehydration/dehydrogenation. Three EPR signals were observed for Cu-Mn-Zn/dealuminated HY and Cu-Mn-Zn/SiO₂ samples at 293 K. In contrast to the spectra recorded at 293 K, only one broad line attributed to Cu-Mn-Zn spinels was visible at 77 K. The EPR signal from pure Cu-Mn-Zn spinels consists only of a single broad line when recorded at 293 K, whereas at 77 K the line is narrower. For all samples subjected to evacuation at high vacuum up to 573 K, the Cu-Mn-Zn spinels were stable. The evacuation at 673 K resulted in a rapid lowering of the intensity of EPR spectrum.
2
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Paramagnetic Centres in Oxidised Coal

100%
Najder-Kozdrowska L., Samoilova R., Kappl R., Hüttermann J., Więckowski A.
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issue 3
475-479
EN
This paper comprises the results obtained by continuous wave (cw)/pulse electron paramagnetic resonance spectroscopy for oxidised coals. The values of EPR linewidths are different for samples of coal treated by different chemical agents. The asymmetric EPR line shape indicates to complex composition of paramagnetic centres in coal. In coal oxidised by HNO_3 big changes of linewidth with temperature were observed. For all samples the spin-lattice relaxation time T_1 was determined by pulse EPR method. The correlation between used chemical agents and the value of T_1 was established.
3
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Groups of Paramagnetic Centres in Reduced and Methylated Low Rank Coal

100%
Pilawa B., Wachowska H., Kozłowski M., Więckowski A., Najder-Kozdrowska L.
Acta Physica Polonica A
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2015
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vol. 128
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issue 3
264-267
EN
Low rank Illinois No. 6 coal was studied by electron paramagnetic resonance EPR spectroscopy. The parameters of EPR spectra (spectroscopic splitting factors g, linewidths ΔB_{pp}, concentrations of paramagnetic centres N) were measured for row and chemically treated coal (demineralized, reduced and methylated samples). The multi-component structure of experimental spectra of this coal was proved. Two groups of paramagnetic centres responsible for broad Lorentzian 1 and narrow Lorentzian 2 lines exist in studied samples. Paramagnetic centres connected with component lines revealed different behaviour during chemical treatments.
4
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Influence of Microwave Power on EPR Signal of Melanin Radical and Copper(II) Ions in DOPA-Melanin Complexes

100%
Najder-Kozdrowska L., Pilawa B., Więckowski A., Buszman E., Wrześniok D.
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EN
Electron paramagnetic resonance spectroscopy EPR was used for examination of microwave saturation in DOPA-melanin complexes with kanamycin and Cu(II) ions. The fast spin-lattice relaxation processes take place in system of paramagnetic metal ions. EPR signal of melanin radical saturated with growing of microwave power used during measurements. After adding Cu(II) ions a shortening of relaxation time is observed for EPR signal of melanin radical.
5
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Triplet States in DOPA-Melanin and in Its Complexes with Kanamycin and Copper Cu(II) Ions

86%
Najder-Kozdrowska L., Pilawa B., Buszman E., Więckowski A., Świątkowska L., Wrześniok D., Wojtowicz W.
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issue 4
613-618
EN
The mono- and biradical forms of DOPA-melanin (DOPA-eumelanin) were studied by EPR spectroscopy in 100-300 K temperature range. The existence of triplet states in DOPA-melanin was proved. The analysis of EPR spectra has shown that in DOPA-melanin and its complexes with kanamycin and Cu^{2+} ions, two kinds of paramagnetic centres exist. The first of them are in doublet ground state with spin S = 1/2 and they obey the Curie law. The paramagnetic centres of the second group are in thermally excited triplet state with spin S = 1 and in this case the Curie law is not fulfilled.
6
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EPR Characteristics of Activated Carbon for Hydrogen Production by the Thermo-Catalytic Decomposition of Methane

86%
Więckowski A., Najder-Kozdrowska L., Rechnia P., Malaika A., Krzyżyńska B., Kozłowski M.
Acta Physica Polonica A
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2016
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vol. 130
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issue 3
701-704
EN
The electron paramagnetic resonance (EPR) method was used to characterize samples of activated coal before and after reactions of the catalytic decomposition of methane and ethanol at temperatures of 1023 K (750°C), 1123 K (850°C) and 1223 K (950°C). The EPR parameters: spectroscopic splitting factor g, peak-to-peak linewidth ΔBₚₚ, and spin concentration c were measured. During the ethanol-assisted catalytic decomposition of methane carbon-located-spin radicals are partially transformed into oxygen-located-spin radicals.
7
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The influence of antibiotic treatment of bitches in oestrus on their attractiveness to males during mating

86%
Dzięcioł M., Niżański W., Stańczyk E., Kozdrowski R., Najder-Kozdrowska L., Twardoń J.
Polish Journal of Veterinary Sciences
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2013
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issue 3
8
Publication available in full text mode
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The efficiency of synthetic sex pheromones in sexual arousal stimulation in domestic dogs

73%
Dzięcioł M., Niżański W., Jezierski T., Szumny A., Godzińska E. J., Ochota M., Stańczyk E., Najder-Kozdrowska L., Woszczyło M., Pieczewska B.
Polish Journal of Veterinary Sciences
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2017
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issue 3
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